(1) Field of the Invention
The present invention relates to an apparatus and a process that is particularly useful for transferring a blow molded object from a molding machine to a collection means. In particular, the present invention relates to the removal of one or more finished or semi-finished blow molded objects, such as a bottle or a container, from one or more blowpins as the mold sections that form the molded object separate. This removal can be accomplished without delay or cycle time loss. Although this invention is particularly applicable to all types of shuttle-type blow molding machines, the present invention may also be used for removing parts from other types of blow molding machines where speed, accuracy and exact positioning of the object is desired or necessary.
(2) Prior Art
Shuttle-type blow molding machines of the prior art that produce hollow objects, such as bottles and containers from thermoplastic materials, have been in use for more than 30 years. These machines produce the hollow objects from a thermoplastic material in the shape of a parison which is captured between two moveable mold sections forming a mold as the mold sections close on the thermoplastic parison. The parison is then cut above the closed mold sections and the mold is immediately shuttled to the blow station where a blowpin is lowered into the mold cavity formed by the mold sections. Air or another suitable gas is then blown into the mold cavity, pushing the thermoplastic material against the walls of the mold. This causes the parison to conform to the shape of the mold cavity to form the hollow object. After an adjusted time for blowing and cooling the molded object, the mold opens and the blown object is left hanging from the blowpin. In the prior art devices, the blown object is then usually stripped off of the blowpin with stripper plates that knock the blown object off the blowpin. The blown object then falls onto a chute or a conveyor belt in an uncontrolled manner.
The prior art also uses two types of methods for removing the blown object from the blowpin in a controlled manner. The first method uses a mechanical gripping device. After the mold sections open and separate, the blown object is left hanging from the blowpin with a bottom flash or tail flash still attached at the seam where the mold sections joined together. A mechanical gripping device which was in position under the mold when the mold was closed, moves up and closes on the tail flash. The mechanical gripping device then moves down and places the blow molded object on the conveyor.
The first method of removing a blow molded object from a blowpin requires the molded object to have the tail or bottom flash attached to the blown object after the mold sections have separated. The bottom flash is removed in a later process. Also, the apparatus for this removal method is permanently attached to the blow molding machine.
The second method removes the blow molded objects from the blowpin, with or without a bottom flash or tail flash still attached to the molded object. In this method, once the mold has opened, the blowpin and the suspended molded object are pulled in an upward direction. This causes the blown object to contact a stop mechanism that results in the object being stripped off of the blowpin as discussed above. The blown object is then placed into a chute which lowers the object onto a conveyor system for transferring the blow molded object away from the molding machine. This removal apparatus is also permanently attached to the blow molding machine.
The prior art has described various types of devices which use a vacuum device to pick up a workpiece to be transferred. Illustrative of the prior art devices are U.S. Pat. Nos. 3,645,658 to DeTroyer; 3,715,796 to DeTroyer; 3,876,352 to DeTroyer et al; 4,424,185 to DeSantis et al; 4,551,193 to Cano; 4,571,320 to Walker; 4,639,207 to Slat et al; 4,680,000 to Nowicki et al; 4,752,206 to Nowicki et al; 4,769,205 to Oles et al; 4,834,643 to Klinedinst et al; 4,886,443 to Klinedinst et al; and 4,968,240 to Binacchi.
U.S. Pat. Nos. 3,645,658 and 3,715,796 to DeTroyer describes a fluid power system for a pickup and discharge mechanism for small manufactured articles or parts, such as made by a powder compacting press. After compacting in a die cavity, the finished parts upon ejection from the die cavities are picked up by a pickup head operatively connected to a suction source for displacement of the finished parts over a discharge port. The finished parts are individually discharged through the discharge port by means of a gentle blast of pressurized air. The suction force to pick up the finished parts is obtained from a flow of air through an appropriate venturi aspirator assembly.
U.S Pat. No. 3,876,352 to DeTroyer et al describes a collecting mechanism for collecting parts made by a powder compacting press. After the parts are ejected from die cavities, the parts are picked up by an aspirator assembly which gently lift the parts through a pick up head. The aspirator assembly is connected to a conduit for transferring the parts to a remotely located discharge station.
U.S. Pat. No. 4,424,185 to DeSantis et al describes a part pick-up head for transferring a part from an ejection station of an apparatus, such as a powder compacting apparatus, to a discharge station. The pick-up head is internally provided with a pair of reciprocating jaws, actuated by pressurized fluid such as compressed air, and arranged to clamp the part at the ejection station with enough pressure to hold the part securely for transfer to the discharge station. At the discharge station, the clamping jaws are spread apart by a return spring when fluid pressure is released. Auxiliary holding means in the form of suction ports above the part are disposed in the pick-up head. The pick-up head also incorporates suction orifices sweeping clean the surface of the die plate over which the pick-up head travels from the ejection station to the discharge station.
U.S. Pat. No. 4,551,193 to Cano describes an apparatus for applying reinforced bottom cups on blow molded plastic containers. The apparatus includes a transfer arm which grasps the outer peripheries of the molded hollow containers, such as bottles. The grasping action is performed by a suction means. The containers are then moved to a mounting station where previously adhesively coated bottom cups are pushed upwardly on to the bottom of the containers. The newly reinforced bottomed container are then discharged from the apparatus.
U.S. Pat. No. 4,571,320 to Walker describes a robot having an opposed set of suction cups used to load and unload precut pieces of sheet molding compound (SMC) from between an upper die and a lower die of a sheet molding press. While the press is molding a piece of SMC, the robot is positioned adjacent to the press, holding a raw piece of SMC with one of the sets of suction cups. On completing of the molding process, the press opens with the molded piece of SMC suspended in a predetermined intermediate position between the dies, adjacent to the upper die. The robot then enters the space between the molded piece and the lower die and if the molded piece is not stuck to the upper die, the robot secures onto the molded piece with the other set of suction cups. If the molded piece has stuck in the upper die, the robot attempts to retrieve the stuck piece of molded SMC. If this attempt is unsuccessful, the robot withdraws the raw piece of SMC from the press to permit removal of the stuck piece. If the molded part is not stuck on the upper die, the robot secures onto the molded piece with the other set of suction cups, unloads the raw piece of SMC onto the lower die and retracts the molded piece from the die.
U.S. Pat. No. 4,639,207 to Slat et al describes an in-mold label dispenser for a blow molding machine. A labeling cycle begins as a label dispensing head moves from a label magazine to the separated halves of a mold. Prior to this, the opposed arms of a label carrier for the label dispensing head engage labels from label magazines with suction cups. The arms then retract and the label dispensing head moves between the mold halves. The label carrier arms then extend to transfer the labels to an inside surface of the mold halves. The labels are held in this position by a vacuum system that communicates with the inside surface of the mold halves. Once the mold vacuum system engages the labels, the suction cups of the label carriers release from the labels and the carrier moves back into the retracted position. The dispensing head then moves back to the label dispenser as the mold halves close on an extrusion of hot plastic. When the extrusion is blown to conform to the mold, the hot plastic activates a heat sensitive adhesive on the labels to secure the labels to the mold.
U.S. Pat. No. 4,680,000 to Nowicki et al describes an apparatus for applying labels to both of the mold halves comprising a mold for a plastic blow molding machine where a plurality of sets of molds are mounted on a rotating wheel. The mold sections or halves are moved toward and away from one another to enclose a parison which is then blown to conform to the shape of the mold to form a plastic container such as a bottle. Labels are attached to the container by a label pickup mechanism comprised of a moveable linkage having a set of vacuum cups that remove a label from a magazine and move the label to a conveyor belt. Each mold half is serviced by a separate linkage system and conveyor belt with the labels held on the belts by a vacuum applied to the belts and, in turn, to any label on the belts. A label placement mechanism services each mold section and includes a reciprocating vacuum head which lifts a label from a belt and moves the label into the cavity of each of the mold sections. The label is then placed in the mold cavity by cutting off the vacuum to the reciprocating head and permitting a vacuum applied through vacuum holes in the mold section to hold the label in position. The mold then closes about the parison and when the parison is blown to conform to the shape of the mold, the labels become adhered to the blown plastic bottle.
U.S. Pat. No. 4,769,205 to Oles et al describes a shuttle-type blow molding machine and in-mold labeling apparatus for placing labels within open mold halves during movement of the mold halves from a blow station to an extrusion station. The machine includes a label transfer assembly having a pair of vacuum transfer heads that are moveable from a retracted position at label magazines, located away from the extrusion station to an extended position between the open mold halves as the mold halves move toward the extrusion station. The mold halves are mounted on a mold transfer carriage which moves between the blow mold and extrusion stations with the labels being transferred to the open mold halves before the mold assembly reaches the mold extrusion station. The labels are held against the recesses in the mold halves until the labels are picked up by vacuum manifolds communicating with the mold recesses. When this happens, the vacuum is removed from the transfer heads and the heads are withdrawn from the recesses. The mold transfer carriage is then moved to the extrusion station where a plastic parison is introduced between the mold halves. The vacuum transfer heads on the label transfer assembly move ahead of the mold transfer carriage so that the introduction of labels into the mold recesses does not slow down the molding process. In this way, the labels are automatically placed within the recesses of the mold halves during the normal cycle of operation of the blow molding machine.
The prior art has also described various types of apparatus that use a vacuum means for transferring a molded object from a mold to a collection device, such as a conveyor. When a molded object is formed between mold sections, a waste flash portion is formed along the seam between the mold sections at the top and the bottom of the object. This flash portion is usually removed from the molded object in a trimming operation after the molded object has been mechanically removed from the mold. Because of this, when the molded object is transferred to a discharge station such as a conveyor, the suction device must engage the molded object on a relatively smooth side, spaced from the flash portion on the bottom of the molded object.
U.S. Pat. No. 4,968,240 to Binacchi describes a device for positioning products extracted from a mold onto a conveyor belt. The device has a main body which supports a second set of suckers that engage the products extracted from a mold by a first set of suckers. An actuation device acts on the second suckers to move them from a first product receiving position to a second position where the product is arranged facing a conveyor belt having product containment pockets.
U.S. Pat. No. 4,752,206 to Nowicki et al describes a take-out assembly for blow molding machines having a continuously rotating turntable, rotating about a horizontal axis. The take-out assembly includes a turntable with a plurality of extending pick-up units having suction cup type engaging pads at their ends. Rotation of the take-out assembly turntable is coordinated with the blow molder turntable such that a suction cup pick-up unit is positioned to engage a side of a workpiece at the desired work station. The pick-up units are radially movable to extend and retract to provide clearance during rotation and to properly engage the workpiece at the discharge station. Workpieces removed from the blow molder turntable are transported by the pick-up assembly into registry with an associated material handling device such as an endless belt type conveyor. This apparatus is quite complicated and expensive to construct and is not adapted to shuttle-type blow molding machines.
U.S. Pat. Nos. 4,834,643 and 4,886,443 to Klinedinst et al both describe a blow molded bottle extraction, trimming and discharge apparatuses that include a rotary turntable and a plurality of bottle transfer units spaced around the turntable. The bottles are molded in an inverted position with the necks of the bottles at the bottom of the mold cavities and the bottom of the bottles at the top of the mold cavities. Each transfer unit has indexing suction cups for picking up the bottles which have been extracted from between mold halves by engaging the tail flash with gripping fingers and lifting the bottles upwardly, a distance above the mold halves. The tail flash is then released by the gripping fingers, the bottles are inverted and moved to a trimming station for removing the neck and tail flash, after which the bottles are moved to a discharge stations. At the discharge station, the bottles are transferred from the indexing vacuum cups to a second set of vacuum cups that deposit the bottles on a conveyor for a subsequent operation. Because the molded bottles are initially extracted from the mold halves by the gripping fingers, even deformed bottles are removed from the mold halves. In this manner, deformed bottles are removed from the mold halves and prevented from ruining subsequently formed bottles.
The problem addressed by the present invention and not by the prior art, is to produce, extract and transfer a finished bottle with the flash removed, from the mold of a blow molding machine. None of the prior art blow molding apparatus have been able to accomplish this result.